Bandwidth and Impedance-Matching Enhancement of Fractal Monopole Antennas Using Compact Grounded Coplanar Waveguide

Abstract

Grounded coplanar waveguides (GCPW) are used to enhance antenna characteristics, namely, reference to the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm VSWR}&lt;2$</tex></formula> bandwidth and the input impedance dynamic range. A printed fractal monopole such as the Sierpinski–Carpet (SC) antenna can be considered as a good candidate for comparing a coaxial-fed system with a GCPW-fed antenna. Conventional SC can be applied at 6.25–8.4 GHz (ref to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm VSWR}&lt;2$</tex> </formula> ), while modified SC matches throughout the 4.65–10.5 GHz (ref to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm VSWR}&lt;2$</tex> </formula> ). Clearly, this new feeding technique changes the behavior of the fractal elements from multiband to wideband. The GCPW-fed antennas have a low crosspolar field and a well-behaved pattern over the enhanced ones. This system of antennas is a possible competitor for the FCC ultrawideband radio short, fat pipe systems. In addition, time-domain analyses are performed to realize the proposed antenna time-domain application over ultrawideband.